OCR GCSE PHYSICS P7

OCR physics Unit 3

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P7A

A SOLAR DAY is 24hrs

A SIDEREAL DAY is 24hrs and 56mins

a solar day is 4 minutes longer than a sidereal

THE MOON TAKES 24hrs and 49mins to appear in the same part of the sky.

IT TAKES 28 DAYS TO COMPLETE ONE ORBIT!!!

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ECLIPSES

  • A SOLAR ECLIPSE IS WHEN THE MOON LINES UP EXACTLY WITH THESUN AND THE EARTH AND BLOCK SUNLIGHT FROM REACHING THE EARTH.
  • A LUNAR ECLIPSE IS WHEN THE EARTH'S SHADOW STOPS THE SUNLIGHT FROM REACHING THE EARTH(THE MOON APPEARS RED)
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CALCULATIONS

  • POWER(dioptres) =1 / focal length(metres)
  • MAGNIFICATION = FO/FE
  • 1 ARCSECOND= 1/3600
  • DISTANCE(pc) = 1/ angle in arcseconds
  • SPEED OF RECESSION(kms) =HUBBLE CONSTANT (s)*DISTANCE(km)
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